commit 43f1bc9d5399e1d659bb5e7ac08dc31d36345d5f
author yuanyunli <yuanyunli@vivo.corp-partner.google.com> Wed Jan 09 16:59:37 2019 +0800
committer Lorenzo Colitti <lorenzo@google.com> Fri Apr 26 22:59:52 2019 +0900
tree f6ead5d89dc31b6a67c9d4fc497525f20232b960
parent ce22e11274d8979228039b1bf71e2ad72a946bf8

Parse the server host name field of the dhcp package

Some hotspot devices will fill in the server host name field of the DHCP
package, such as iphone. Parsing the server host name of the DHCP
package can help identify ios hotspots.

Bug: 120584519
Test: 127423755
Test: builds, boots, wifi works
Change-Id: Idbe10c36332ce421f1bba93eb87e9e1e12463088

core/java/android/net/DhcpResults.java

diff --git a/core/java/android/net/DhcpResults.java b/core/java/android/net/DhcpResults.java
index a33f3fc..65bc75b 100644
--- a/core/java/android/net/DhcpResults.java
+++ b/core/java/android/net/DhcpResults.java
@@ -64,6 +64,8 @@
     @UnsupportedAppUsage
     public int mtu;
 
+    public String serverHostName;
+
     public DhcpResults() {
         super();
     }
@@ -97,6 +99,7 @@
             vendorInfo = source.vendorInfo;
             leaseDuration = source.leaseDuration;
             mtu = source.mtu;
+            serverHostName = source.serverHostName;
         }
     }
 
@@ -129,6 +132,7 @@
         vendorInfo = null;
         leaseDuration = 0;
         mtu = 0;
+        serverHostName = null;
     }
 
     @Override
@@ -139,6 +143,7 @@
         str.append(" Vendor info ").append(vendorInfo);
         str.append(" lease ").append(leaseDuration).append(" seconds");
         if (mtu != 0) str.append(" MTU ").append(mtu);
+        str.append(" Servername ").append(serverHostName);
 
         return str.toString();
     }
@@ -154,6 +159,7 @@
         return toStaticIpConfiguration().equals(target.toStaticIpConfiguration())
                 && Objects.equals(serverAddress, target.serverAddress)
                 && Objects.equals(vendorInfo, target.vendorInfo)
+                && Objects.equals(serverHostName, target.serverHostName)
                 && leaseDuration == target.leaseDuration
                 && mtu == target.mtu;
     }
@@ -179,6 +185,7 @@
         dest.writeInt(mtu);
         InetAddressUtils.parcelInetAddress(dest, serverAddress, flags);
         dest.writeString(vendorInfo);
+        dest.writeString(serverHostName);
     }
 
     @Override
@@ -193,6 +200,7 @@
         dhcpResults.mtu = in.readInt();
         dhcpResults.serverAddress = (Inet4Address) InetAddressUtils.unparcelInetAddress(in);
         dhcpResults.vendorInfo = in.readString();
+        dhcpResults.serverHostName = in.readString();
         return dhcpResults;
     }
 

packages/NetworkStack/src/android/net/dhcp/DhcpPacket.java

diff --git a/packages/NetworkStack/src/android/net/dhcp/DhcpPacket.java b/packages/NetworkStack/src/android/net/dhcp/DhcpPacket.java
index d7ff98b1..c5b75f8 100644
--- a/packages/NetworkStack/src/android/net/dhcp/DhcpPacket.java
+++ b/packages/NetworkStack/src/android/net/dhcp/DhcpPacket.java
@@ -309,6 +309,11 @@
     protected final byte[] mClientMac;
 
     /**
+     * The server host name from server.
+     */
+    protected String mServerHostName;
+
+    /**
      * Asks the packet object to create a ByteBuffer serialization of
      * the packet for transmission.
      */
@@ -848,6 +853,7 @@
         Inet4Address ipDst = null;
         Inet4Address bcAddr = null;
         Inet4Address requestedIp = null;
+        String serverHostName = null;
 
         // The following are all unsigned integers. Internally we store them as signed integers of
         // the same length because that way we're guaranteed that they can't be out of the range of
@@ -989,9 +995,9 @@
         packet.get(clientMac);
 
         // skip over address padding (16 octets allocated)
-        packet.position(packet.position() + (16 - addrLen)
-                        + 64    // skip server host name (64 chars)
-                        + 128); // skip boot file name (128 chars)
+        packet.position(packet.position() + (16 - addrLen));
+        serverHostName = readAsciiString(packet, 64, false);
+        packet.position(packet.position() + 128);
 
         // Ensure this is a DHCP packet with a magic cookie, and not BOOTP. http://b/31850211
         if (packet.remaining() < 4) {
@@ -1192,6 +1198,7 @@
         newPacket.mT2 = T2;
         newPacket.mVendorId = vendorId;
         newPacket.mVendorInfo = vendorInfo;
+        newPacket.mServerHostName = serverHostName;
         return newPacket;
     }
 
@@ -1251,6 +1258,7 @@
         results.vendorInfo = mVendorInfo;
         results.leaseDuration = (mLeaseTime != null) ? mLeaseTime : INFINITE_LEASE;
         results.mtu = (mMtu != null && MIN_MTU <= mMtu && mMtu <= MAX_MTU) ? mMtu : 0;
+        results.serverHostName = mServerHostName;
 
         return results;
     }